<!doctype html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>switch</title>
	<script type="text/javascript">

	var a = 90;

	switch(a){
		case  90:
		alert("a等于90")
		break;
		case  80:
		alert("a等于80")
		break;
		case  70:
		alert("a等于70")
		break;
		default:
		alert("一个都没有匹配到")
	}

	</script>
</head>
<body>
	
</body>
</html>